FIG. 1 shows a communication system which services a demand generated from a set of mobile users 2. The communication system includes base stations 1 which handle communications with the mobile users 2 in defined geographic areas 3 know as cells. Specifically, each base station 1 functions as a communication bridge between all mobile users 2 within its cell 3 and a mobile switching center (MSC) 4. The MSC 4 coordinates all the activities of the base stations 1 and connects the base stations 1 to a public switched telephone network (PSTN) 5.
Communication systems, such as the one shown in FIG. 1, are designed to service an estimated user demand. User demand is conventionally estimated by focusing on the calling frequency of the mobile users 2. User demand based on these behavioral patterns is generally known in the art as user call demand. User call demand is usually represented by factors such as calls/user, message-services/user, and pages/user, where each of these factors are calculated for a given time period during which the communication system experiences its heaviest use.
Factors which represent user call demand are modeled by using spatial and temporal distributions. FIG. 2 shows an example of a spatial distribution for user call demand. In FIG. 2, based on known demographics, various geographic areas are designated as having a high population density (HPD) of users, where other areas are designated as having a low population density (LPD) of users. The HPD areas are generally those geographic areas which will produce a large number of calls such as business districts. The LPD areas, on the other hand, are those geographic areas which generally produce a small number of calls such as a suburbs.
FIGS. 3(a) and 3(b) are examples of temporal distributions used to model user call demand. The temporal distributions shown in FIGS. 3(a) and 3(b) are based on the spatial distribution shown in FIG. 2. Specifically, FIG. 3(a) shows an example of a temporal distribution which represents calls/user for the HPD areas, whereas, FIG. 3(b) shows an example of a temporal distribution which represents calls/user for the LPD areas.
A review of FIGS. 3(a) and 3(b) indicates, for example, that the peak number of calls/user in the HPD areas is estimated to be 1.7 at 6:00 PM, and the peak number of calls/user in the LPD areas is estimated to be 0.95 at 7:00 PM. Based on these peak values, and the peak values for the other factors discussed above, a complete model of user call demand can be developed.
FIG. 4 shows a conventional method for designing a communication system. In the conventional method, a first step 6 involves modeling user call demand in accordance with the techniques discussed above. The next step 8, which is sometimes referred to as RF planning, involves designing a grid of base stations and cells to accommodate the estimated user call demand. And the third step 10, which is sometimes referred to as network planning, involves designing one or more MSC networks to service the base stations and cells. The result of the conventional method is a preliminary design of a communication system 12.
The conventional method for designing a communication system does, however, have certain drawbacks. The conventional method only takes into account user call demand and fails to address other behavioral patterns of users which could result in a demand being placed on the communication system. In particular, while the conventional method accounts for a demand based on the calling frequency of the user, it fails to properly account for a demand based on the mobility of the user.
Many shortcomings result when user mobility demand is not adequately considered during the design of a communication system. First, by not taking into account the user mobility aspect of demand, a resulting communication system will be ill-equipped to service a peak user demand. Moreover, when the mobility factors are not considered during the design phase, the resources of the communication will not operate in an optimal manner. These two drawbacks, among others, will ultimately result in a communication system which does not adequately and effectively service the user community.